Bug 2502303 (CVE-2026-63858)

Summary: CVE-2026-63858 kernel: netfilter: nf_tables: add hook transactions for device deletions
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's netfilter (nf_tables) subsystem. This vulnerability could lead to a denial of service for network filtering operations. The issue occurs because the process of deleting network hooks improperly modifies a protected list, which can disrupt how network configuration information is read. This could be exploited by an attacker to cause instability or unresponsiveness in the system's network filtering capabilities.
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Description OSIDB Bzimport 2026-07-19 15:02:51 UTC 
In the Linux kernel, the following vulnerability has been resolved:

netfilter: nf_tables: add hook transactions for device deletions

Restore the flag that indicates that the hook is going away, ie.
NFT_HOOK_REMOVE, but add a new transaction object to track deletion
of hooks without altering the basechain/flowtable hook_list during
the preparation phase.

The existing approach that moves the hook from the basechain/flowtable
hook_list to transaction hook_list breaks netlink dump path readers
of this RCU-protected list.

It should be possible use an array for nft_trans_hook to store the
deleted hooks to compact the representation but I am not expecting
many hook object, specially now that wildcard support for devices
is in place.

Note that the nft_trans_chain_hooks() list contains a list of struct
nft_trans_hook objects for DELCHAIN and DELFLOWTABLE commands, while
this list stores struct nft_hook objects for NEWCHAIN and NEWFLOWTABLE.
Note that new commands can be updated to use nft_trans_hook for
consistency.

This patch also adapts the event notification path to deal with the list
of hook transactions.
Comment 1 Keith Grant 2026-07-21 18:48:35 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026071933-CVE-2026-63858-618e@gregkh/T